1. Field of the Invention
The present invention relates to transient signal detectors, and in particular, to transient signal detectors for detecting transient signal excursions which exceed threshold levels in both positive and negative directions.
2. Description of the Related Art
Many circuit applications can benefit from, or in many cases absolutely require, some form of transient signal detection whereby signals within the monitored signal path which exceed some predetermined threshold and which are frequently transient in nature can be reliably detected. This will allow appropriate responsive action to be initiated, such as filtering or suppression of such transient signals.
One such circuit application is that of a subscriber line interface circuit (SLIC) for telecommunications. Signal transients in a telecommunication environment are quite common. For example, aside from any transient signals introduced by the operating environment (e.g., electrical motors, lightning strikes, ground loops, etc.), transients due to transitions between on-hook and off-hook conditions and normal dialing impulses caused by rotary telephones are often encountered. For many applications, such transients can be problematic and result in unreliable or otherwise unacceptable circuit performance.
Monitoring transient signals in a SLIC application, while already difficult, can be further complicated by the fact that the signal environment is differential in nature due to the "tip" and "ring" signal connections. Accordingly, transient signals with both positive and negative differential signal polarities can be and often are encountered. Accordingly, it would be desirable to have a simple transient signal detection circuit which can detect both positive and negative signal transients in a differential signal environment.